What is a Catalytic Converter?

What is a Catalytic Converter?

11th Jul 2017

If your vehicle was built after the mid-1970s, it probably has a catalytic convertor. Invented by French mechanical engineer Eugene Houdry, this otherwise simple component has proven instrumental in reducing emissions and subsequently improving air quality in congested cities. So, what is the catalytic convertor exactly and how does it operate?

A catalytic converter is a component used on modern day vehicles with internal combustion engines that's designed to convert toxic exhaust gasses to less toxic pollutants. It does this by catalyzing a redox reaction, which is essentially an oxidation and reduction reaction. Catalytic convertors are typically filled with a chemical catalyst, such as platinum and palladium, that triggers this redox reaction.

Technical jargon aside, catalytic convertors aren't used for performance; rather, they are used to reduce toxic emissions created by internal combustion engines.

Just because it's not necessary for a combustion engine to operate doesn't necessarily mean that you can remove the catalytic converter from your vehicle. On the contrary, the Environmental Protection Agency's (EPA) clean air laws require most vehicles in the United States to have them. If your vehicle has a bad or otherwise failing catalytic convertor, you'll need to fix it ASAP. Failure to do so could result in hefty fines, not to mention the negative impact it has on your health.

So, how do you know if your vehicle's catalytic convertor is failing?

Some of the most common signs of a failing catalytic convertor include the following:

  • Cracked exhaust manifold
  • Reduced engine performance
  • Reduced exhaust airflow
  • Weak acceleration
  • Ratting noise (coming from the catalytic convertor)
  • Check engine light

Normally, a catalytic convertor will last for a decade or longer. However, there are times when the internal components will wear down and degrade, resulting in a less effective conversion process. Common reasons why catalytic convertors go bad include degraded piston rings, failing valve seals, warped engine block and blown head gasket. Additionally, spark plugs that misfire may cause unburned fuel to enter the exhaust system, which can also degrade the catalytic converter and cause it to fail.

Unfortunately, replacing the catalytic convertor isn't cheap. While exact costs vary depending on the vehicle make and model, location of service and market rates, you can expect to pay between $700 and $1,300 on average.

Hopefully, this gives you a better understanding of catalytic convertors and how they work.

Photo credit: Frank Derks